lili wang , shaohui guo , guoxiao yin
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Research on lubrication performance of micro-textured journal bearing
based on fluent
Lili Wang a, Shaohui Guo b, Guoxiao Yin c
Shandong University of Science and Technology, Qingdao 266590, China.
awang-ly-ly@163.com, bm17806258200@163.com, c598925940@qq.com
Abstract. The micro-textured surface technology has obvious effect on improving the lubrication
performance of the journal bearing. In this paper, a 3D micro-textured journal bearing model is
established by fluent and compared with non-textured smooth journal bearing. The effect of
circumferential total texture and partial texture of different positions in bearing area on bearing
lubrication performance is analyzed. Results show that circumferential total texture and partial
texture can effectively improve the bearing capacity of bearing and reduce the friction coefficient, and
there is a reasonable and effective range for the quantity, position and density of micro texture.
Keywords: Micro-texture; journal bearing; bearing capacity; friction coefficient.
1. Introduction
Because of the good performances such as large carrying capacity, stable operation and high
operating accuracy, journal bearing is widely used in the engineering fields such as steam turbine,
railway locomotive, high precision lathe and aerospace. It has great significance for extending the
service life of the sliding bearing and improving the stability of the mechanical system to study the
lubrication characteristics of the sliding bearing, and improve continuously the working performance
of the bearing. The micro-textured surface technology has obvious effect on improving the bearing
capacity of the journal bearing, reducing the friction coefficient and forming the oil film. Many
scholars have done a lot of research on the application of micro-textured surface technology in journal
bearing.
Hamilton et al. [1] studied the theory and experiment of micro texture through processing a series
of micro bumps on the mechanical seal by the etching technique, proposed that dynamic pressure
effect is obtained by micro convex on the surface of friction pairs. The influence of different texture
shapes including rectangles, circles, triangles on working performance of journal bearing was
researched based on Reynolds equation by Rahmani et al. [2]. Brajdic-Mitidieri et al. [3] used the
CFD method to carry on the numerical simulation for the infinite long slide bearing which only had
one rectangle texture. Yang [4] analyzed the effect of different geometric parameters and sectional
shapes of micro texture on the lubrication performance of journal bearing by numerical analysis
method. Qi [5] established an infinite long radial bearing lubrication model, and researched the
influences of surface texture quantity and sizes on bearing performance by CFD method based on N-S
equation. Zhao et al. [6] researched the effect of partial groove texture on the lubrication performance
of bearing using CFD model. In consideration of the cavitation and turbulence effect, Yin et al. [7]
studied the influence of geometrical parameters and distribution characteristics of surface micro
texture on the bearing performance of journal bearing. Qiu [8] built the simulation model by Fluent,
and studied the relationship between the shape of the cross section and the carrying capacity, the
effect of the texture ratio and speed on the bearing capacity.
This paper builds the 3D micro-textured journal bearing model by fluent based on N-S equation,
the effect of quantity, position and density of surface micro-texture on bearing lubrication
performance is analyzed. The research results enrich the understanding of the effect of micro texture
technology on the performance of journal bearings, and there is great significance for the application
of surface texture technology in journal bearing.
International Conference on Artificial Intelligence and Engineering Applications (AIEA 2016)
Copyright © 2016, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
Advances in Computer Science Research, volume 63
213
2. Model
In this paper, the model of hydrodynamic sliding bearing is studied. As shown in Figure 1, radius
of bearing bush R1 is 20 mm, diameter of axle R2 is 19.9 mm, initial deflection angle ψ is 40o,
eccentricity e is 0.06 mm, θi is the starting angle of circumferential coverage angle, Δθ is the
circumferential coverage angle. The lubricating condition of the sliding bearing is incompressible,
constant temperature and laminar flow state, lubricating method is oil lubrication, the parameters of
lubricating oil is as following: density p is 785 kg/m3, dynamic viscosity η is 0.035 Pa.s. As shown in
Fig. 2, the paper adopts the groove micro texture with cross section shape of rectangular, the length of
texture unit L is 20 mm, height D is 0.05 mm, width W is 0.3 mm. N represents the quantity of micro
texture.
The setting of boundary conditions is as following: pressure exit boundary conditions are used, two
end of the oil film is set to the pressure outlet, stress is the atmospheric pressure by default, the inner
surface of the bearing bush is set to a fixed wall, the surface of axle is set to a revolving wall, and
rotation rate is n=600 rad/s, the direction of rotate is clockwise, the region between the two surfaces is
the calculated fluid region.
The pressure distribution of oil film can be obtained by analyzing the finite element model of
micro-texturing journal bearing using fluent, then the bearing capacity, friction force and friction
coefficient of the bearing in the corresponding state can be solved.
The calculation of bearing capacity
The bearing capacity can be obtained by integrating the oil film pressure:
dyxp dFy (1)
Fig.1 Diagram of journal bearing Fig.2 Diagram of micro-textured unit
The calculation of friction force
The friction force can be obtained by integrating the viscous shear stress acting in the journal:
dydxf F (2)
The calculation of friction coefficient
The friction coefficient can be obtained by the ratio of friction force and bearing capacity:
dydxp
dydx
F
Ff
f
y
(3)
Advances in Computer Science Research, volume 63
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3. Results and analysis
3.1 The circumferential total texture on journal bearing
The circumferential total texture of journal bearing is set to rectangular texture in circumferential
position uniformly, θi=0o, Δθ=360o, the texture number N is set to 0,6,8,10,15,18,20,and N=0
represents smooth bearing without texture .
(a) Maximum pressure of oil film (b) Bearing capacity
(c) Friction coefficient
Fig.3 The lubrication performance of bearing with different number textures
The (a), (b), (c) of Fig. 3 represents maximum pressure of oil film, bearing capacity, and friction
coefficient respectively when the circumferential total textures of journal bearing has different
numbers. As shown in Fig. 3, compared with the smooth bearing, both the maximum pressure and
bearing capacity can be improved through processing circumferential total texture, the friction
coefficient obviously reduces by this method, the lubrication performance of bearing is improved
significantly. This is because that micro texture is conducive to producing dynamic pressure
lubrication when circumferential total textures of journal bearing has different numbers, and micro
texture can store lubricating oil and reduce friction force. With the increase of the number of texture,
the lubrication performance of bearing reaches the best; but when the number of texture exceeds 18,
the bearing capacity and maximum pressure of journal bearing with circumferential total texture are
lower than the smooth bearing without texture, and the friction coefficient is greater than smooth
bearing. Results show that the lubrication performance of bearing including bearing capacity,
maximum pressure and the friction coefficient can be improved when bearing has proper amount and
distribution density of circumferential total texture; but there is a reasonable and effective range for
the distribution density of micro texture, it can produce adverse effect on performance of bearing
when density of micro texture exceeds a certain range.
3.2 The partial texture on journal bearing
In consideration of the limitations of the texture processing technology and the actual engineering
application of journal bearing, the partial texture not only saves the processing cost but also reduces
the difficulty of processing texture. So it has an important significance for engineering application to
research the influence of the partial texture on journal bearing. As shown in Tab.1, this paper choices
three positions in the bearing zone as studying object (position 0 indicates smooth bearing), micro
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texture which covers a circumferential area of 1/2,1/4,1/12 is processed respectively. θi is the starting
angle of circumferential coverage angle , Δθ is the circumferential coverage angle, N is the quantity of
micro texture.
Table 1 The different positions of the partial texture Different
positions θi Δθ
Number
N
Maximum pressure
/MPa
position 0 0o 0o 0 1.632
position 1 0o 180o 10 1.713
position 2 90o 90o 10 1.873
position 3 150o 30o 20 1.953
(a) Bearing capacity (b) Friction coefficient
Fig.4 The lubrication performance of bearing with different position textures
The fig.(a)and (b) of Fig. 4 represents bearing capacity and friction coefficient respectively when
the partial textures of journal bearing has different numbers. The Tab.1 shows that the maximum
pressure in oil film of bearing with partial texture is bigger than smooth bearing without texture; as
can be seen from Fig. 4(a) and (b) that the bearing capacity of three positions with partial texture is
bigger than smooth bearing, and friction coefficient is smaller than smooth bearing, this illustrates the
partial texture can improve the lubrication performance of journal bearing; from the numerical change
trend by comparing with the three positions, the cover area of position 2 is less than position 1, and the
number of texture (the distribution density) is smaller than position 3, but the bearing capacity of
journal bearing is improved obviously and friction coefficient is the minimum. The above results
show that the lubrication performance of journal bearing can be improved more effectively when the
bearing area has partial texture in the reasonable position, and there is an optimal position and
covering area for improving the bearing capacity. For a fixed size of texture, the improving of
lubrication performance has a certain relationship with the quantity and density of micro texture, there
is an optimal quantity and density of micro texture for improving the lubrication performance of
journal bearing.
4. Discussion & Conclusions
In this paper, to reveal the effects of surface texture on the performance of journal bearing, the
effect of circumferential total texture and partial texture on bearing lubrication performance is
analyzed through establishing a 3D micro-textured journal bearing model. The main conclusions are
the following:
a) The circumferential total texture can improve the bearing capacity of journal bearing and the
maximum pressure of oil film, reduce the friction coefficient effectively, but there is a reasonable and
effective range for the quantity and distribution density of micro texture. It can produce adverse
effects on performance of bearing when density of micro texture exceeds a certain range.
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b) The reasonable partial texture in bearing area of journal bearing can also improve the lubrication
performance, and there is an optimal position and density of micro texture to increase the bearing
capacity and reduce the friction coefficient.
The influence of surface texture on the journal bearing is influenced by many factors, so further
research needs to consider various factors, and simulation research in this paper has some limitations.
The theoretical analysis and experimental methods should be more used to analysis the micro texture
technology based on simulation research, it has greater guiding significance for the practical
application of micro texture technology in engineering.
Acknowledgements
This work is supported by National Natural Science Foundation of China (NO. 51305242) and supported by
SDUST Research Fund (NO. 2015JQJH104)
References
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Engineering, 1966, 88(1):177-185.
[2] Rahmani R, Mirzaee I, Shirvani A, etal. An analytical approach for analysis and optimization of
slider bearings with infinite width. Tribology International, 2010, 43:1551-1565.
[3] Brajdic-Mitidieri P, Gosman A D, Ioannides E, et al. CFD analysis of a low friction pocketed pad
bearing. Journal of Tribology, 2005,127 (4):803-812.
[4] Yang Huarui. Study on the effects of surface texture and bubbly oil performance of journal
bearings. Beijing: Beijing Institute of Technology, 2014.
[5] Qi Ye, Chang Qiuying, Li Huiting, Shen Zongze. Research on load carrying properties of surface
textured journal bearing. Lubrication Engineering, 2012, 37(12):36-42
[6] Han Lei, Zhao Yuncai. CFD-analysis of partiall surface groove texture on hydrodynamic
lubrication. China Surface Engineering, 2013, 26(06):112-118.
[7] Yin Minhu, Chen Guoding, Gao Dangcheng, Wang Lin. Effects of three types of surface texture
on the performances of journal bearing. Journal of Harbin Institute of Technology, 2016,
48(1):159-164.
[8] Qiu Xiaocong, Chen Guoquan .CFD-analysis of groove texture on hydrodynamic lubrication.
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